What are diamonds?

Diamond is the crystallised form of pure carbon (99.95% to 99.98%), the strongest mineral on earth, and one of the oldest substances known to man. The chemical formula of diamond is C which is the chemical symbol for the element carbon.

The earth is estimated to be 4.5 billion years old. Most of the diamonds we find today started to form between 1 billion and 3.3 billion years ago under intense heat (around 1,204°C) and immense pressure, more than 150km below the earth’s surface in the mantle, an area consisting of volcanic magma.

Then, hundreds of millions of years ago, powerful volcanic eruptions pushed the diamonds closer to the earth’s surface. As the magma travelled up to the surface it ripped off pieces of the mantle taking the diamonds, embedded inside the crystallised host rocks, with it.

The funnel-shaped areas carved out by the magma eruptions are called kimberlite pipes, named after the first formation discovered in Kimberley, South Africa.

Diamond ore, in its roughest form, doesn’t look like the shiny nuggets on engagement rings. Diamonds must be sorted, cut and polished to bring out their lustre. On average, 250 tonnes of ore must be mined in order to produce a single carat gem quality polished diamond.

Rough diamonds come in all shapes and sizes, colours and purities. They may be transparent, translucent or opaque. The larger, whiter and cleaner the diamond, the rarer it is. However, premium prices can be commanded by coloured diamonds, which can be blue, pink, green, yellow, brown, orange, violet, black or grey.